This invention relates to an intrusion monitoring apparatus, more particularly to the apparatus for automatically providing an audible and/or visual alarm in response to the detection of an intrusion into an area which is being monitored.
Hitherto, the detection of an intrusion into the area which is being monitored included the fact that a person monitors at all time the monitoring screen using a television camera and a remote monitor unit. In order to avoid the person judging the intrusion, a kind of an automatic apparatus was developed. Such apparatus was the one wherein photoelectric elements are installed at various points on the surface of the monitoring television screen so that the change of the brightness of the television screen surface is detected as the change of the outut from the photoelectric cells to provide an alarm signal. Because the photoelectric cells were set up on the monitoring screen, a portion of the screen was masked. Further, it was necessary that the monitor screen always be left on.
Therefore the object of the invention is to avoid the disadvantages of the prior art apparatus.
Other objects and advantages of the invention will be clear from the description given below with respect to the drawings.